1. Field of the Invention
The present invention generally relates to a method of recycling a developer for office automation equipment. More specifically, the present invention relates to a method of recycling a double component developer that contains a carrier and a toner.
2. Description of the Related Art
Recently environmental issues are getting more significant.
There is an urgent need of recycling products, parts, and materials to utilize them efficiently in light of effective use of resources and reduction in wastes for a company.
Recycling practice can be categorized into the following approaches.
An approach 1 is captive reuse, according to which a user who uses a product reuses part of the product, such as parts, by him/herself. Captive reuse is assumed that a user can practice easily, as a result, this approach can achieve the largest reduction in environmental stress as well as the highest cost effectiveness.
An approach 2 is reuse of a product, according to which a used product is collected from the market (hereinafter, collected device) to be reused as a recycled device via a certain recycling process. This approach allows most part of the used product to be reused as it is, and can reduce an environmental stress considerably.
An approach 3 is reuse of a part, according to which a part or a unit is removed from a collected device to be reused as a part or a unit within a product newly manufactured. This approach can omit a manufacturing process of the part or the unit, which is initially manufactured with a substantial amount of energy, thereby reducing environmental stress substantially.
An approach 4 is material recycle, according to which a collected device is disassembled and sorted into each unit of materials, which is to be reused as a recycled material via a certain treatment. This approach can be categorized into two: closed-loop material recycle brings the recycled material to be reused as a material of a product in the same field as the collected device; and open-loop material recycle brings the recycled material to be reused as a material of a product in another field.
An approach 5 is regeneration of a raw material, according to which a collected device is disassembled, sorted, and ultimately brought back to a raw material to be reused. This approach can achieve zero waste.
An approach 6 is energy recovery, according to which plastics are incinerated to effectively utilize thermal energy arising from incineration.
In terms of reduction in environmental stress, the most desirable approach in the above 1 to 6 is the approach 1, then followed by 2, 3, . . . , and 6 in this order. Therefore, how to sustain recycling with a more desirable approach in the six approaches is critical for a company to promote recycling in practice. In fact, for example, a product cannot semi-permanently remain being treated only with captive reuse of the approach 1, although it is the most desirable. After a certain period of time, this approach has to be abandoned for the product. Because a function of the product is degraded after a certain period of time, and the function is no longer functional for markets (or users), recycling the product with this approach inevitably loses its economic value.
In such a case, recycling the product that has been performed with an upper approach shifts to a lower approach. For example, a product that has been recycled with the captive use is going to be recycled with the approach 2 or a lower approach. Thus, the product is recycled with the lower approach for a certain period of time, and when the product is degraded, then recycling shifts a still lower approach, and so on.
Therefore, performing only part of the approaches 1 to 6 is insufficient, but the whole approaches need to be performed in recycling. In practice, the approaches 1 to 6 have to be performed across related products in parallel. The reason for this is that the approaches 1 to 6 are different depending on a type of each product. Moreover, even if focusing on one product, a level of recycling approach for each of parts and units can vary.
Japanese Patent Application Laid-open No. 2000-181958 titled “Recycling System” discloses the above recycling. A concept of the recycling method and system is clarified in a flow (comet circle) shown in FIG. 8 of Japanese Patent Application Laid-open No. 2000-181958. In a practice of recycling, how to bring this basic concept (the comet circle) into operation is vital.
Particularly, in cases of office automation equipment, such as photocopy machines and facsimiles, used products includes a developer that is used as supplies as well as a machine body and its parts. Such an image forming device generally employs a dry type of electrostatic copying in recent days, in which the developer is generally powder. Therefore, one of significant aspects for office automation equipment is how to establish a recycling system of a powder (a developer) in practice.
To involve a company in a sustainable environmental activity, it is significant to form the environmental activity itself consistent with an economic interest. It is desirable if costs of the environmental activity are decreased as much as possible, and furthermore, the environmental activity and a profit making activity are carried out on the same axis, so that the environmental activity itself becomes profitable in the end. In other words, the recycling approaches 1 to 6 are desired to be operated for value rather than as an onerous contract.
One of conventional proposals, for example, Japanese Patent Application Laid-open No. 2001-290311, discloses recycling of a developer for office automation equipment, titled “Method and Apparatus for Separating and Recycling a Coating Resin and a Magnetic Substance of a Carrier for Electrophotography.”
The publication suggests a method of a reuse of a carrier. The carrier includes a magnetic substance and a coating resin, and forms a developer with a toner. The coating resin can be separated from the magnetic substance through a treatment under a condition of supercritical water or subcritical water. The method is very innovative due to a small environmental influence arising from the condition for recycling (reuse of the carrier). However, the method has an economical disadvantage. Setting the condition of supercritical water or subcritical water results in a relatively large cost compared with producing a new carrier. Consequently, a company cannot make a profit from a carrier recycled by the method proposed above. Therefore, the method can be used only within a substantially limited scope.
An economical disadvantage (despite of a dramatic improvement in environmental aspects) can be observed also in other conventional examples. For example, Japanese Patent No. 3133146 titled “Recycling Method for Electrophotographic Developer” also brings about the same situation. The publication also suggests a reuse of a carrier. However, to separate a waste toner attached on a waste carrier, a heating treatment and a solvent treatment (cleaning) are performed, thereby resulting in a substantial increase in a cost which cannot generate a profit compared with producing a new carrier.
A common disadvantage that some of the conventional technologies hold lies in that material components of a waste carrier (i.e. an unfunctional carrier, such as a used item or an off-specification item) cannot be comprehensively utilized. In the examples above, to reuse the carrier, a coating material over a toner (a toner attached on the carrier) or the carrier is treated as a residual, which means a non-profitable item, i.e. a non-recyclable item. If the residual portion is able to be converted into a profitable portion, the economical disadvantage can be significantly improved in a recycling practice.
The inventors have been proposing several approaches that manages environmental protection and an economic interest in consistent each other by utilizing components of materials comprehensively in recycling of a developer.
For example, Japanese Patent Application Laid-open No. 2004-033960, titled “Toner Recycling Method and Toner Recycling System” proposes a system of manufacturing a flux for steelmaking by mixing a off-specification toner discharged from a factory or a used toner, with aluminum dross, aluminum dust, and aluminum residue. When using the system, recycling in which no useless component is left from the waste toner, i.e. recycling that manages environmental protection and an economic interest in consistent, can be achieved. However, the publication proposes only an optimal recycling system for a toner in a developer (a carrier and a toner), which is not a proposal for a carrier. For example, a carrier does not serve for a steelmaking flux at all.
Therefore, following to an example disclosed in Japanese Patent Application Laid-open No. 2004-027125, in which the whole subject materials are completely used as a policy of recycling, a recycling system needs to be established by taking a carrier into account.
According to Japanese Patent Application Laid-open No. 2004-027125, titled “Molding Material and Molding Product, Manufacturing Method thereof, and Recycling Method of Waste Toner”, a waste toner is used as a molding material by melting and kneading it with modified polyphenylene ether. The waste toner preferably contains a component that contains a resin of styrene acrylonitriles. Accordingly, the waste toner that cannot be provided as a commercial product can be utilized effectively to produce a molding product that has an excellent tensile strength, an excellent elasticity in bending, and an excellent bending strength, and can be widely used for applications and in fields at low cost. However, a subject of this proposal is also a toner, not recycling of a carrier. Furthermore, the proposal seems to manage environmental protection and an economic interest in consistent at first glance, however, an inadequacy remains in an environmental aspect. Specifically, a resin of styrene acrylonitriles and modified polyphenylene ether are very special materials, which can be used only for quite limited parts as described in the proposal. Thus, a material recycle is available for at once, but when recycled parts are put into the market, and again brought into used parts afterwards, a demand for the parts is hardly continued at the initial level. Therefore, a multi-layer material recycle is not maintained, as a result, those parts are inevitably thrown into energy recovery. This results in nothing but destroying possibility of the multi-layer material recycle (in which a material recycle is repeated for avoiding exhaustion of resources) of modified polyphenylene ether itself and a toner itself.